Field of the Invention
The present invention relates to an antenna, especially an array antenna according to the preamble of the independent claim.
Discussion of Related Art
Array antennas are known from the prior art. These are used for directional transmission and reception of electromagnetic waves.
U.S. Pat. No. 6,861,996 from Microface Co., Ltd. was first published in 2002 and is concerned with a waveguide slot antenna of three-layer construction, which is intended to have a strongly directional characteristic and a high antenna gain. The three plates that form the individual layers are manufactured from plastic and then coated with metal, so that the surfaces are electrically conductive. Alternatively, the individual plates can be made of metal. The waveguide slot antenna comprises a lower first plate, which comprises a first half of a distribution tree on the upper surface. A central second plate comprises a second half of the distribution tree, which in the mounted state cooperates with the first half of the distribution tree. The second plate also comprises through openings. Among other things, because of the distribution tree integrated in the second plate on the reverse side, this has significant fissuring. The third upper plate also has significant fissuring because of the openings necessary for transmission. The parts of the antenna are relatively difficult to manufacture with the required tolerances.
U.S. Pat. No. 3,950,204 from Texas Instruments Inc. was published in 1973 and is concerned with a method for connecting two metallic surfaces with good electrical conductivity, e.g. of plate antennas. The method is described as an alternative to dip soldering, because it can be carried out at significantly lower temperatures. The plate antenna used as an example has a two-layer metal construction.
GB2247990 from British Satellite Broadcasting was first published in 1990 and is concerned with an array antenna with a two-layer construction with a lower and an upper plate. The upper plate comprises recesses, which are used as a horn antenna. The lower plate comprises a distribution tree that is used for signal distribution to the horn antenna. The two plates are joined to each other by soldering or welding. It is a disadvantage that the plates have a complex, likewise significantly fissured construction.
CN2739818Y from the Bejing Yijia Yingye Information Engineering Co. was published in 2005 and discloses a planar antenna with high antenna gain and about 1024 transmitting elements. The antenna has a layered structure. The individual plates are joined by bolts.
US2007241962A from Hitachi Ltd. was first published in 2005 and discloses a radar antenna for use in automobiles. The antenna comprises a metal plate with a plurality of slots. Absorbers for radio waves, which are disposed between the slotted metal plate and the actual antenna, are used to detect directional changes. The slotted metal plate and the antenna are disposed at a distance apart.
EP1 006608A from Technisat Digital GmbH was first published in 2000 and discloses a multilayer antenna arrangement with patch elements that are formed in a conductive top layer. First stimulation elements are formed in a second conductive layer lying thereunder and second stimulation elements are formed in a third conductive layer. The first stimulation elements comprise first supply lines oriented in a first direction and the second stimulation elements comprise second supply lines oriented in a second direction orthogonal to the first direction. Each supply line is oriented to the associated patch element and is electromagnetically coupled to it. The antenna comprises a relatively complex structure with very many layers.
U.S. Pat. No. 5,321,411A from Matsushita Electric Works Ltd. was first published in 1992 and relates to a planar antenna for linearly polarized waves. The antenna has a multilayer structure. The antenna is suitable for a wavelength range of around 500 MHZ.
DE101 50086 from Uhland Goebel was published in 2003 and relates to an array antenna. According to the description the antenna should have a high working bandwidth and a small overall thickness. The described array antenna comprises a regular arrangement of openings in a first electrically conductive or conductively coated body. A second body comprises chamber-like recesses of dual mirror-symmetrical form and is connected to a large area of the first body. The chamber-like recesses are each associated with at least four openings of the first body. The chamber-like recesses have centrally disposed openings on the rear, which form a connection to the second large area of the second body and are used for supply. The antenna has a relatively complex structure and is unsuitable for frequencies in the range 70-80 GHZ, whilst economical manufacture is no longer possible.